1. Field of the Invention
The present invention relates to mosaic ink recording devices.
2. Description of the Prior Art
Mosaic ink recording devices are known in the art such as, for example, the recorder described in German OS No. 2,527,647. Such recorders print alphanumeric characters and images in punctiform representation by ejecting ink droplets from closely-spaced nozzles or jets disposed in rows in front of the recording medium. Each nozzle has an ink inlet opening in front of which is disposed a piezoelectric transducer in the form of a strip or a bar. The free end of each transducer is normally spaced slightly away from the inlet opening and when ink is to be ejected from the particular nozzle associated therewith, a voltage is applied to the transducer causing the transducer to move toward the inlet opening thereby forcing recording fluid through the nozzle from which it is ejected onto the recording medium. The individual transducers are formed by the teeth of a comb-like piezoplate, the plate material also being bilaminar, consisting of piezoceramic material and a carrier material.
In conventional mosaic printers of the type described above, a substantial degree of mechanical coupling is present between the transducer teeth, and particularly between adjacent transducer teeth, via the common comb base of the piezoplate. If a transducer tooth is excited by a voltage so as to bend that particular transducer, adjacent teeth also bend because of the mechanical coupling to a lesser extent and with a certain delay. Because of the mechanical coupling further remote teeth are also influenced, however the excitation of such teeth decreases with the distance from the excited transducer tooth. In conventional recorders of the type identified above, the comb base of the piezoplate is mounted on a carrier which is part of the recording head, so that this portion of the piezoplate cannot be bent. If the comb base of the piezoplate to be clamped on the carrier of the recorder is somewhat bent, the plate may easily break during clamping.
Because of the mechanical coupling between the teeth, the possibility also exists that ink may be transferred from the region surrounding adjacent teeth to the region in front of the nozzle of the excited transducer tooth. In order to achieve a good recording quality, each tooth, prior to its activation, must be in a rest position. If two adjacently disposed teeth are to be activated immediately in succession, the initially activated tooth should not be permitted to set the adjacent tooth into oscillation. If this occurs, the time spacing between the activation pulses must be made sufficiently long such that the oscillation of the adjacent tooth has decayed to a sufficient degree. This results in a significant decrease in the maximum recording speed.